Work hardening alloy steel



Patented Oct. 16, 15

WORK HARDENING ALLOY Albert Paul Qagnebin, Red Bank, N. 3., assignor to The International Nickel Company, Inc., New York, N. Y., a corporation of Delaware No, Drawing. Application April 14, 1943, Serial No. 483,049

7 Claims. (01. 75-128) The present invention relates to work hardening alloy steels.

It has been proposed to use Hadfields manganese steel containing about 10% to 14% manganese for many applications where wear resistance and abrasion resistance were desired, for example, in digging and crushing machinery requiring toughness and abrasion resistance. However, Hadflelds austenitic manganese steel suflered from several shortcomings. It required a toughening heat treatment, i. e., the steel had to be heat treated ln order to prevent brittleness. The steel developed useful properties only after water quenching from about 1900 F. This drastic treatment often caused cracks and usually caused distortion requiring subsequent straightening.

Moreover, its application was restrictedto section sizes under about 5 inches thick because the quenching stresses developed in the heavier sections promoted internal cracks leading to early failure. In addition, it could be produced only in certain limited types of furnace equipment. It could not be produced in the acid electric furnace, which is in common use in jobbingfoundries, but was produced only in a basic electric furnace or by mixing molten steel and separately melted term-manganese. Furthermore, it required the use of large quantities of the strategically necessary manganese. Although many attempts were made to remedy the aforementioned and other shortcomings, none, as far as I am aware, was entirely successful when carried into practice commercially,

I have discovered that the prior art shortcomings can be avoided and that new and unexpected results can be obtained by using a special combination of elements in controlled proportions.

It is an object of thepresentinvention to provide a cast steel alloy which hardens rapidly when bruised or deformed.

It is another object of the invention to provide an alloy steel which is tough in the as cast; condition and which can be hardened to a high level of hardness by cold deformation.

It is a further object of the invention to provide a cast alloy steel which is tough and wear resistant.

It is also an object of the invention to provide a cast alloy steel of the work hardening type which does not require a heat treatment to prevent brittleness.

It is still another object of the invention to provide an alloy steel of the work hardening type which does not require the large amounts of manganese required heretofore.

The invention also provides an alloy steel 01' the work hardening type which can be produced with furnace equipment not suited for the pro Other objects and advantages of the invention will become apparent from the following description.

Generally speaking, the present invention provides an alloy steel which is tough in the as cast condition, which work hardens rapidly, and which can be produced in the acid electric furnace, in addition to other furnace equipment. The iron base alloy steels provided by the present invention contain about 3% to 10% nickel, about 1.5% to 3% or 3.5% chromium, about 2% to 6% manganese, and about 0.8% to 1.7% or 1.8% carbon. A more preferred range is about 4% to 8% nickel, about 1.7% to 2.75% or 3% chromium, about 3% to 5.5% manganese, and about 1% to 1.5% carbon. In addition, the alloy steels of the present invention may contain small amounts of mol dental or minor constituents and impurities added for known purposes or present as a result of good steel making practices, e. g., special deoxidizers, silicon, phosphorus, sulphur, etc. Thus, the steels normally will contain about 0.1% up to 1%, or even more, of silicon, e. g., about 0.4% to 0.5%. It is to be understood that when the term balance substantially all iron isv used herein, it is not desired to exclude incidental or minor constituents or impurities which may be present in such amounts as occur in commercial products or in amounts not adversely aifecting the desired properties of the alloy steel.

In carrying the invention into practice, the nickel, chromium and manganese contents must be so correlated that the minimum amounts of all the elements are not used in any one composition. Similarly, the maximum amounts of all the elements should not be used in one componickel,

termed herein the "alloy factor and is defined sition. If the minimum amounts of nickel, chromium and manganese are used, toughness in the as cast condition is sacrificed; whereas, if the maximum amount of each of these elements is used, the rapid work hardening properties are deleteriously affected. I have found that the sum ofthe nickel, chromium and manganese must be maintained within a certain range to obtain the desired results. The correlation of chromium and manganese has been a with Hadfields manganese steel because the high quenching stresses developed by the different cooling ratesof thick and thin sections cause I cracking. The absence ofheat treatment and attendant distortion also; means. that castings o1 the new alloy steel will 'fltproperly in the units for which they are intended. Hatiflelds manganese steel cannot be'produced in an acid lined furnace because the manganese in the steel oxidizes rapidly and rea'ctswith the lining of the furnace causing a rapid erosion of the refractory and large losses in the manganese content. Since the new alloy contains less thanabout 6% manganese, preferably about 4.5%v manganese, and one-ballot this quantity can; -bemelted in the furnace andthe other halt added to the ladle, its production in acid electrioffurnaces oflers little diillculty. V v v In actual practice, the alloy steels of the present invention preferably .containi'at least nickel, e. g-.. about 5.5% to 1% nickel, at least 2% chromium, e. gqabout 2% j to 2.5% chromium, at least 3.5% manganese, 'e.=g.,;'about 4% to 5% -me.nganes'e,-iaimi at least 1'.1%.carbon.,e. 8., about 11.1% to 1.4% carbon.

The composition ot theiallo steels provided by the present inventionisf sd cbntrolled that the g5 castjst'eel has a 'microstructure' containing sub.- stantiai amounts ofaustenitewhichiis sufllciently unstable t'ojtransforinwhen bruisedforsubjected maya'lsolcontsin son: in the proportion -.-o i-..-no p toughe l is the inthe spastf'cbndition. In general; the steel; willf be:- -sli ghtly magnetic; v v In, the steels of "the: resent; invention, Ichro- 1 mium; .withih the sfet" iorthhereinabove. ,fis essential.to"achieve 'TthedQred results. I. have made the jsurprising ;-.di'seovery that chro- .m r u e arb e netw rk an ap v i essentialto securetbughness' lathe as cast con-'- 'dition-in an alloy steel which rapidly work harden. Likewise, asuiiiciently'high carboncontent 1 1s 7 essential t obtain desired results. In general,'the-rangs set forth-arecriticaljand if j the alloy content :au be qy hemm um or maximuinset forth, the des d' ;co'mblnation 'oi p toughness and rapid-wot ardening'properties' is'no longer obtained; H I 'lllustrativefeigamples i "steels, having compo.-

siti ons contemplatedby the presentinvention are set forth in the table.

Per cent- Percent 1 The as past toughness orthesesteelsis very,

. high yin both light" and heavyjsections. The toughness can be improved further byfch'ill I casting which refines the grain and increases the austenitic stability." Chilling the working face on particularly severe applications is adventageous. The toughness can also be improved further by water quenching from-a. high temperature The'steels of the .presentiginvention work h en *as'well as austenitic, manganese steel. Thus, Steel No. 1 hasan as castlhardness of about 10 to 14 Rockwellfq which'increased to about 43 Rockwell 0" after a given amount of hardnesses as high as a The steels provided by the present inventionare adaptable in cast or wrought term for use in,

cold deformation. A austenitie manganese steel containing 14.5% manganese and 1.3% carbon,

and having an as casthardness of about 10 Rockwell "C," had a hardness of about 38 Rockwell "C" after being subjected to about the same amount of cold deformation as was Steel No; 1. with more severe'cold deformation the steels of the present invention. e. g., Steel No. -1,' develop Rockwell C or more.

digging, crushing and grinding applications requiring toughness and abrasion resistance. Ex-

amples of suitable applications include ball mill liners, jaw plates in crushers, rolls. etc.

Although the present invention has been'described in conjunction with preferred embodi ments, it is to be understood that modifications and variations may be resorted to without depart- 5 ing from the spirit and scope of the invention, as

those skilled in the art will readily understand. Such variations and modifications are considered to be within the purview and'scope or the invention and the appended claims.

I claim:

1. An alloy steel containing about 5% .to 7% nickel, about 2% to 2.5% chr0mium,ab o1it 3 .5% j to 5% manganese, about 1.1% to 1.4% carbom; j andthe'balancesubstantiallyalliron.

An l y t e n n nafsbcut 1% 155%.". nickel, about 1.7% to 3% chromium, ,aboutg3%.

to 5.5% manganese, the'sum o't thenickel co'ntent, the chromium content, and twice the f g nese content being atleast about 13% and not i; more than about 18%. about 1% to 1.5% carbon, I

and the balance substantially all iron.

' 3. An alloy steel containing about 3% i:o10% nickel, about 1.5% to 3.5% chromium, about 2% to 6% manganese, the sum of the nickel'content,

the chromium content and twice the manganese content being at least about 13% and notmore than about 18%, about 0.8% to 1.8% carbon, and

the balance substantially all iron.

4. An alloy steelcontaining about 3% to 10% nickel, about 1.5% to 3.5% chromium, about 2% a to 6% manganese. the'sum oi nickel-content, .the chromium content and twice the manganese content being at least about 11%- and not more than about 21%, about 0.8% m 1.21% carbon, and.

the balance substantially all iron;

5. As an article of manufacture, a castlns made of an alloy steel containing about 5%,t'o 7% nickel,

about 2% to 2.5% chromium, about 3.5% 5% manganese, about1.1% to 1.4% carbon, andjtho balance substantially all iron.

6. As an article or manufacture, a i of an alloy steel containing'about 4% to-8%niclr el, v f about 1.7% to 3% chromium, about 3% $0 5.5% 1

manganese, the sum of the nickel content. the 'jI chromium content, and twice the; mansauese' content being at least about 13% and not'more:

than about 18%. about 1% tit-1.5 91: carbomand thebalancesubstantiaily'all iron. 1 'v 7. ls-an article of manufacturaa casting made of an alloy steel containing 7 about 3%T to;1il% nickel, about 1.5% to -3.5% chromium, about-3%" I to 6% manganese. the sum of the nickel content '1 the chromimn-content andtwice themangancse 1 content being at least about 11% not more than about. 21%, about0.8% to1.8 carbon;, and

thebalance substantially allirou. i

. AL'BERT PAUL GAGNEBIN. 

